1. Technical Field
The present application relates to an ultraviolet irradiation apparatus that irradiates a fluid with ultraviolet light and ultraviolet irradiation method.
2. Description of the Related Art
To date, ultraviolet irradiation apparatuses for irradiating water with ultraviolet light have been used to sterilize water. For example, Japanese Unexamined Patent Application Publication No. 2011-55898 describes one of such apparatuses.
To date, apparatuses utilizing a low-pressure mercury lamp have been used to sterilize water. Typically, low-pressure mercury lamps emit ultraviolet light having wavelengths of 185 nm and 254 nm. Ultraviolet light in this wavelength range is usually called deep ultraviolet light (DUV). It is known that, among wavelengths of light emitted from a low-pressure mercury lamp, deep ultraviolet light having a wavelength of 254 nm has particularly high sterilization capability. Basically, a light source of a mercury lamp is a point light source or a linear light source, and deep ultraviolet light is emitted radially from the light source.
Japanese Unexamined Patent Application Publication No. 2011-55898 describes a technology in which a surface light source is used to emit deep ultraviolet light. In the technology described in Japanese Unexamined Patent Application Publication No. 2011-55898, a surface light source is obtained by irradiating a metallic fluoride with an electron beam. This document also describes a method of sterilizing water by using a surface light source having a surface on which a plurality of winding water channels are formed.